80 ROPINESS DT WATTLE BARK INFUSIONS, 



and so did phase A2 with the acetate. The phases Al and B2 with the acetate 

 did not become ropy. 



From these two tests, it appears that the limiting strength of the acetate for 

 cheeking ropiness in bark infusions lies between 2 and 3 parts per 10,000. 



Still one more test was made with bark and water containing 1. 2, 3 and 4 

 parts of acetate of sodium per 10,000, the liquids being seeded with phases Al, 

 A2, and B2. Ropiness developed in the tests seeded with phases A2 and B2 

 containing one part per 10,000 but not in the stronger solutions. Phase Al did 

 not produce ropiness in the weakest solution. 



The conclusion that we come to from al consideration of all the tests is that 

 crystalline sodium acetate, when added to the water used for extracting wattle 

 bark, in the proportion of three parts of salt to 10,000 of water or 3 pounds to 

 1,000 gallons will prevent the formation of ropiness in wattle bark extract. 



The Natuie of the Eopt/ Substance. 



An attempt was made to obtain the slime in bulk by growing the bacterium 

 A in fluid media containing dextrose or glycerin, but the quantities of slime were 

 very small. This may possibly have been caused by autodigestion as noted in 

 the various experiments with sjoithetic media, but of this I have no definite in- 

 formation to offer. More successful results were got by gi-owing the organism 

 on solid agar. Several drojis of a broth culture of the organism was smeared 

 on plates of a medium containing glycerin 5 %, meat-extract 1 So potassium 

 nitrate 0.1 % and sodium phosphate 0.2 %. The first gi-owth obtained in a 

 few days was yellow, loose, and was easily scraped off. The second growth that 

 came up was translucent and elastic. It adhered w^th more or less tenacity to 

 the agar, and some bits could not be removed. It was noted that the toughness 

 increased with time, and the reason for this was explained later when it was 

 learned that glycerin caused the phase Al to alter progressively to A2, the more 

 insoluble phase. 



The collection of films was treated with alcohol and filtered ; the coagulum 

 was treated with water in which it simply swelled up; there was no solution. 

 The swollen slime was heated in an autoclave at three atmospheres' pressure for 

 half an hour when a solution and a sediment were obtained. The liquid was fil- 

 tered with the aid of aluminiimi hydrate, and the filtrate was concentrated by 

 evaporation. A portion sufficiently dilute to enable light to pass through was 

 tested in the polariscope and found to give a reading of -|-2.i2'' in a 200 mm. 

 tube. Thus the gum was dextro-rotatory. The solution was further evaporated 

 to a mucilaginous consistency and tested dropwise with various reagents. 



Coagulation was effected with alcohol, basic lead acetate, ammoniacal lead 

 acetate, ferric chloride and phosphotungstic acid, but the following had no act-on: 

 lead acetate, baryta water, lime water, milk of lime, copper sulphate, the same 

 followed by sodium hydrate. Fehling's solution, iodine, tannic acid, sodium hydrate 

 or sulphuric acid. These are the general reactions with the autoclaved slimes, 

 i.e., slimes which by the autoclave treatment have l)een separated into a soluble 

 gummy matter nn<l into coagulated proteid. The natural, uncoagulated ropy sub- 

 stance would behave i|uite differently. In one case where a slime was autociaved 

 for five and a half houi-s. coagulation was effected only with basic lead acetate 

 and by phosphotungstic acid. 



